package se.jagvetintedu;

//
// In the 2020 grid below, four numbers along a diagonal line have been marked in red.
//
// 08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
// 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
// 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
// 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
// 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
// 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
// 32 98 81 28 64 23 67 10 *26 38 40 67 59 54 70 66 18 38 64 70
// 67 26 20 68 02 62 12 20 95 *63 94 39 63 08 40 91 66 49 94 21
// 24 55 58 05 66 73 99 26 97 17 *78 78 96 83 14 88 34 89 63 72
// 21 36 23 09 75 00 76 44 20 45 35 *14 00 61 33 97 34 31 33 95
// 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
// 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
// 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
// 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
// 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
// 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
// 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
// 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
// 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
// 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48

// The product of these numbers is 26 x 63 x 78 x 14 = 1788696.
//
// What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 20x20 grid?
//
//

public class Problem11 {
	
	private class Grid {
		private Integer x, y;
		private Integer[][] theGrid;
		
		public Grid(Integer x, Integer y, String content) {
			this.x = x;
			this.y = y;
			theGrid = new Integer[this.x][this.y];
			
			String[] parts = content.split(" ");
			
			if (x*y != parts.length) {
				throw new IndexOutOfBoundsException();
			}
			
			int dx = 0, dy = 0;
			for (String s : parts) {
				theGrid[dy][dx] = new Integer(s);
				dx++;
				if (dx == x) {
					dx = 0;
					dy++;
				}
			}
		}
		
		public Integer largestProduct(int x, int y, int count) {
			Integer result = 0;
			Integer product = 1;
			boolean right = false;
			boolean left = false;
			boolean up = false;
			boolean down = false;
			
			// Check right
			if (x+count < this.x) {
				right = true;
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y][x+i];
				}
				if (product > result) {
					result = product;
				}
			}
			
			// Check left
			if (x-count >= 0) {
				left = true;
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y][x-i];
				}
				if (product > result) {
					result = product;
				}
			}
			
			// Check up
			if (y-count >= 0) {
				up = true;
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y-i][x];
				}
				if (product > result) {
					result = product;
				}
			}
			
			// Check down
			if (y+count < this.y){
				down = true;
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y+i][x];
				}
				if (product > result) {
					result = product;
				}
			}
			
			// check up/left
			if (up && left) {
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y-i][x-i];
				}
				if (product > result) {
					result = product;
				}
			}
			
			// check up/right
			if (up && right) {
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y-i][x+i];
				}
				if (product > result) {
					result = product;
				}
			}
			
			// check down/left
			if (down && left) {
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y+i][x-i];
				}
				if (product > result) {
					result = product;
				}
			}
			
			// check down/right
			if (down && right) {
				product = 1;
				for (int i = 0; i < count; i++) {
					product *= theGrid[y+i][x+i];
				}
				if (product > result) {
					result = product;
				}
			}
						
			return result;
		}
	}
	
	private String content = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 " +
			                 "49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00 " +
			                 "81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65 " +
			                 "52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91 " +
			                 "22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80 " +
			                 "24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50 " +
			                 "32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70 " +
			                 "67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21 " +
			                 "24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72 " +
			                 "21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95 " +
			                 "78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92 " +
			                 "16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57 " +
			                 "86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58 " +
			                 "19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40 " +
			                 "04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66 " +
			                 "88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69 " +
			                 "04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36 " +
			                 "20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16 " +
			                 "20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54 " +
			                 "01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48 ";
	
	private Integer solve() {
		Integer max = 0;
		
		Grid myGrid = new Grid(20, 20, content);
		
		for (int x = 0; x < 20; x++) {
			for (int y = 0; y < 20; y++) {
				
				max = Math.max(max, myGrid.largestProduct(x, y, 4));
			}
		}
		
		return max;
	}
	
	public static void main(String args[])
	{
		System.out.println("Project Euler, problem 11");
		
		Problem11 solution = new Problem11();

		System.out.println("The greates product of four adjacent numbers is: " + solution.solve());
	}
}
